Traditionally, the process of orthodontics is carried out with braces and similar appliances using brackets and metal wire, in which teeth are attached to individual brackets, which are then attached to a wire. The tightness of the wire is adjusted as needed by the orthodontist; this method, which has been refined over the decades, allows for detailed control over where the brackets are pulled in what direction at how much force, and allows for easily customizable treatment as needed.
However, due to reasons such as intrusiveness in the mouth and poor aesthetics, a number of other options are currently being explored by those in the field. Among those are tray aligners, which work by placing down a thin polymer-based aligner molded to the shape of the patient's teeth; the aligner will then guide the teeth through applied force to the intended result orchestrated by digital manipulation of these teeth in sequential manner. A well-known example is Invisalign®, a polymer-based aligner based on U.S. Pat. No. 5,975,893 (Chishti et al.) and other related patents. The advantage of such aligners is that they provide less intrusion in the mouth than traditional braces, allowing for the patient's further comfort in day-to-day tasks such as eating, brushing, and flossing.
A weakness of this method is that, by itself, it cannot effectively account for the necessary differential force that must be applied to different teeth for certain tooth movements. Conventional orthodontic methods generally require a designated anchor point to use as a basis from where force is exerted, thus allowing for direct control over the direction and amount of force applied on the teeth. However, with tray aligners as described above, generated force is entirely dependent on reciprocal anchorage, meaning that a group of teeth is pulled, pushed, torqued and rotated against adjacent groups of teeth. As such, some unwanted movement from adjacent teeth (anchor teeth) may be inevitable and should be accounted for during treatment. Additionally, the effectiveness of force application is dependent on the quality of anchor teeth, which may not be adequate for certain tooth movements.
Bodily tooth movement during the space closure in extraction cases, torque control, anterior intrusion, rotation of posterior teeth and root movements are known to be challenging with the traditional clear aligner appliances (e.g., the ones described in U.S. Pat. No. 5,975,893). Aligners such as Invisalign® are created by vacuum-fitting a sheet of polymer over a mold of the teeth, which results in the polymer having a roughly even thickness over the aligner. Thus, tooth movement is largely guided by reciprocal force between the teeth towards an overall goal, and may result in unintended side effects, such as lack of proper force magnitudes and incorrect direction due to multiple components exerting force onto each other.
Therefore, there is a need for aligners that overcome the aforementioned short-comings of the clear aligner.
Therefore, the embodiments described below address the above-identified issues and needs.